[Pseudohypoaldosteronism: Pathogenesis, pathophysiology, and therapy].
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Aldosterone↗
Biomedical subjects
Keiko Arai
Publications and source records attributed to Keiko Arai.
[CRF family peptides in feeding behavior and eating disorders].
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Amino Acids↗
Surgical excision of neovascularization in retinal angiomatous proliferation.
BACKGROUND: We report the postoperative outcomes of surgical neovascularization excision in patients with retinal angiomatous proliferation (RAP). METHODS: Nine eyes of eight patients with RAP who underwent surgical excision of neovascularization were studied. Surgical indications were as follows: RAP diagnosed by fluorescein and indocyanine green angiography, foveal or perifoveal neovascularization, preoperative visual acuity of 0.1 or less, Yannuzzi's stage II with detachment of retinal pigment epithelium (RPE) or stage III, and leakage on late-phase fluorescein angiography. After cataract surgery, vitreous surgery and neovascularization excision were conducted, followed by fluid-air or fluid-gas exchange. RESULTS: Visual acuity was 0.02-0.1 before surgery and 0.03-0.2 after surgery. Macular hole formation was seen in one eye but did not lead to retinal detachment. In two eyes, subretinal bleeding occurred during excision leading to vitreous bleeding after surgery. Although defects of the RPE and choriocapillaries were observed after surgery, the exudation and bleeding were absorbed. CONCLUSIONS: In stage II RAP cases with RPE detachment, surgical excision maintains constant postoperative visual acuity but results in defects of RPE and choriocapillaris; therefore, other treatment options should be examined. Surgical excision of stage III RAP seems to be promising, as postoperative visual acuity remains stable after neovascularization removal in those advanced pathologic situations.
Aged↗
Both corticotropin-releasing factor receptor type 1 and type 2 are involved in stress-induced inhibition of food intake in rats.
RATIONALE: Stress-induced inhibition of food intake is reportedly blocked by a selective corticotropin-releasing factor (CRF) type 1 receptor (CRF1) antagonist, suggesting the involvement of CRF1 in the inhibitory mechanism. CRF1 and CRF2 are considered to function in the inhibition of food intake by CRF-related peptides with different time courses. OBJECTIVES: This study was designed to clarify whether CRF2 is also involved in stress-induced inhibition of food intake and to examine the relation of CRF1to CRF2 in the inhibitory mechanism. METHODS: Antisauvagine-30 (AS-30), a selective CRF2 antagonist, and/or CRA1000, a selective CRF1 antagonist, were pre-administered intracerebroventricularly and intraperitoneally, respectively, to male Wistar rats deprived of food for 24 h before the animals were exposed to a 1-h period of stressors and food intake in 1 h after stress exposure was examined. The effect of both antagonists on locomotor activity was also examined. RESULTS: Pre-administration of 5-30 microg of AS-30 attenuated inhibition of food intake induced by restraint, electric footshock or emotional stress using a communication box. CRA1000 also attenuated the restraint-induced inhibition of food intake at doses of 5 and 10 mg/kg body weight. The reversal of restraint-induced inhibition of food intake by co-administration of AS-30 and CRA1000 was not larger than that by AS-30 or CRA1000 alone. Both antagonists did not affect locomotor activity. CONCLUSIONS: These results suggest that not only CRF1, but also CRF2, are involved in stress-induced inhibition of food intake, and that both subtypes of CRF receptor function probably in series in 1 h after stress exposure.
Animals↗
Effects of food restriction on peroxisome proliferator-activated receptor-gamma and glucocorticoid receptor signaling in adipose tissues of normal rats.
In adipocytes, peroxisome proliferator-activated receptor (PPAR)-gamma activates adipocyte differentiation and glucocorticoid (GC) stimulates the expression of PPAR-gamma mRNA. The local tissue concentrations of GC, in turn, are modulated by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). To clarify the change of energy metabolism in condition of reduced energy intake, we investigated whether food restriction alters the adipocyte size and levels of PPAR-gamma, GC receptor (GR), and 11beta-HSD1 mRNA expression in the white adipose tissues of normal rats. Male Wistar rats weighing 340 g were housed under free feeding or 20% reduction of food intake for 2 or 14 days. We found that 2-day food restriction did not cause any change in the mean size or number of adipocytes in the omentum, while 14-day food restriction decreased the size and increased the number of adipocytes. In addition, the levels of PPAR-gamma2, GR, and 11beta-HSD1 mRNA expression in the omentum were lower in the food-restricted rats after 2 days, while they did not differ after 14 days. Also, after both 2 and 14 days, plasma concentrations of free fatty acid (FFA) were higher in the food-restricted rats than in control rats. Finally, plasma concentrations of adrenocorticotropin (ACTH) and corticosterone were the same in the both groups after 2 days, although they were higher in the food-restricted rats after 14 days. These results suggest that adipocyte differentiation in the omentum of food-restricted rats is attenuated after 2 days but recovers after 14 days, resulting in an increase in the number of small adipocytes. It is also likely that lipolysis induced during the 14-day period of food restriction decreased the size of adipocytes. Further, food restriction may affect the efficiency of local GC effects by altering GR and 11beta-HSD1 mRNA expression. Also, higher levels of plasma GC and recovery of GR and 11beta-HSD1 mRNA expression may contribute to the recovery of the levels of PPAR-gamma2 mRNA expression in the omentum and result in the recovery of adipocyte differentiation.
11-beta-Hydroxysteroid Dehydrogenase Type 1↗
Corticotropin-releasing factor receptor type 1 is involved in the stress-induced exacerbation of chronic contact dermatitis in rats.
Cutaneous diseases such as psoriasis and atopic dermatitis are worsened by psychic stress. We attempted to clarify the involvement of the corticotropin-releasing factor (CRF) receptor (CRFR) in stress-induced exacerbation of chronic contact dermatitis in rats. Male Wistar rats, in which chronic contact dermatitis had been induced by 2,4,6-trinitro-1-chlorobenzene (TNCB), were exposed to a 1-h period of electric foot-shock following intraperitoneal administration of CRA1000, a selective CRFR type 1 (CRFR1) antagonist, or vehicle everyday for 9 days. Histological examination of the skin showed that the epidermis significantly thickened and the number of mast cells in the dermis significantly increased by repeated exposure to stress, and that these changes were blocked by CRA1000. These results suggest that CRFR1 is involved in the stress-induced exacerbation of chronic contact dermatitis.
Animals↗
Ghrelin mRNA and GH secretagogue receptor mRNA in human GH-producing pituitary adenomas is affected by mutations in the alpha subunit of G protein.
OBJECTIVE: Ghrelin and its receptor, growth hormone secretagogue (GHS) receptor (GHSR), are expressed in the normal pituitary gland and various types of pituitary adenoma. Somatic mutations in the subunit of Gs alpha protein (gsp), which led to a constitutive activation of adenylyl cyclase, are reported in GH-producing pituitary adenomas. We analysed the relationship between ghrelin mRNA and GHSR mRNA expression levels in gsp mutation-positive and -negative GH-producing pituitary adenomas. PATIENTS: Pituitary adenoma tissue was obtained at surgery from 20 patients with acromegaly. METHODS: The expression levels of human ghrelin mRNA and GHSR mRNA were quantified using a competitive RT-PCR method. To detect the gsp mutations, amplified Gs alpha subunit cDNA fragments were sequenced directly using RT-PCR method. RESULTS: There was no significant difference in the expression of ghrelin mRNA between mutation-positive and -negative adenomas. The expression of GHSR mRNA was significantly lower in gsp mutation-positive than -negative adenomas. There was a significant negative correlation between the levels of ghrelin mRNA and GHSR mRNA expression in mutation-negative adenomas; no such correlation was found in mutation-positive adenomas. CONCLUSION: These results suggest that GHSR mRNA expression is downregulated by ghrelin in gsp mutation-negative GH-producing pituitary adenomas, and that changes in intracellular signalling pathways in gsp mutation-positive GH-producing pituitary adenomas affect the expression of G protein-coupled receptors such as GHSR. The absence of negative correlation between ghrelin and GHSR expression might be induced by lowered GHSR expression in gsp mutation-positive GH-producing adenomas.
Adenoma↗
Effect of chronic administration of a CRF(1) receptor antagonist, CRA1000, on locomotor activity and endocrine responses to stress.
Corticotropin-releasing factor (CRF) is involved in the regulation of stress responses. The actions of CRF in the brain are mediated through two distinct CRF receptor subtypes, CRF(1) and CRF(2) receptors. In the present study, we examined the effects in rat of chronic administration of a nonpeptidic CRF(1) receptor-selective antagonist, CRA1000, 2-[N-(2-methylthio-4-isopropylphenyl)-N-ethylamino]-4-[4-(3-fluorophenyl)-1,2,3,6-tetrahydropyridin-1-yl]-6-methylpyrimidine), on locomotor activity, feeding behavior and the hypothalamic-pituitary-adrenal axis. Chronic CRA1000 treatment significantly decreased locomotor activity in the dark phase of the diurnal cycle. However, chronic CRA1000 treatment showed no effect on food and water intake, or on body weight. After a 10-day period of CRA1000 treatment, plasma concentrations of adrenocorticotropic hormone (ACTH) and corticosterone in basal conditions and under immobilization stress were no different from those in rats treated with vehicle. However, CRA1000 administered 2 h before immobilization stress significantly reduced ACTH and corticosterone responses to stress with no effect on basal ACTH and corticosterone concentrations. These results suggest that CRF(1) receptors are involved in the regulation of locomotor activity during the dark period, but are not involved in the regulation of feeding behavior under non-stressful conditions. Furthermore, the results suggest that a 10-day treatment with CRA1000 does not affect hypothalamic-pituitary-adrenal axis activity either under basal conditions or after acute stress.
Adrenocorticotropic Hormone↗
Functional polymorphisms in the mineralocorticoid receptor and amirolide-sensitive sodium channel genes in a patient with sporadic pseudohypoaldosteronism.
Pseudohypoaldosteronism (PHA) is characterized by urinary salt-wasting in infancy resulting from a congenital resistance to aldosterone involving the genes for the mineralocorticoid receptor (MR) and the amiloride-sensitive sodium channel (ENaC). We identified, in a Japanese patient with sporadic PHA, three homozygous substitutions in the MR gene: G215-->C215, A754-->G754 (Ile180-->Val180), C938-->T938 (Ala241-->Val241), which had previously been reported to occur in healthy populations. Luciferase activities induced by MR with either G215-->C215, Ile180-->Val180, or Ala241-->Val241 substitution were significantly lower than those for wild-type MR with aldosterone at concentrations ranging from 10(-11) to 10(-9) M, 10(-8) M, or 10(-11) to 10(-6) M, respectively. A homozygous A-->G substitution of the donor splice site of alphaENaC intron 4 was found in the patient. The corresponding cDNA exhibited a normal structure, suggesting that this substitution does not alter the splice. The results suggest that each of three MR polymorphisms identified in our patient is functionally and structurally heterogeneous. We hypothesize that two or more "functional" polymorphisms, any of which exhibits only slight effects on MR or ENaC function and is alone incapable causing PHA, may in the right allelic combination induce the negative salt-conservation characteristic of PHA.
Aldosterone↗
[Genetic disorders caused by gain or loss of function of the mineralocorticoid receptor].
Aldosterone has crucial role for sodium conservation in the kidney, salivary glands, sweat glands and colon. It exerts its effects via the mineralocorticoid receptor (MR) which belongs to the member of the nuclear receptor superfamily. Recently, genetic disorders have been reported to be caused by gain or loss of function of the MR. The amino acid substitution of the ligand-binding domain(S810L) of the MR resulted in the early-onset hypertension exacerbated by pregnancy. This mutation results in constitutive MR activity and alters receptor specificity for progesterone. Pseudohypoaldosteronism type 1 (PHA1) is characterized by congenital aldosterone resistance of the kidney and/or other mineralocorticoid target tissues, resulting in excessive salt wasting. The heterozygous nonsense or missense mutations were identified in the patients with autosomal dominant PHA1 and a sporadic PHA1. This suggests that the full expression of the MR is necessary for salt conservation.
Humans↗